1. Field of the Invention
The present invention relates to a two-dimensional manipulating robot which is useful in application for surface mount placements, inspection and parts assembling or arrangements.
2. Description of Related Art
For example, in determining which parts or electronic devices are present or absent on printed circuit boards or in effecting required performance tests on selected parts or electronic devices on printed circuit boards, use is made of a two-dimensional manipulator which comprises an X-axial arm and two opposite Y-axial arms slidably attached to the opposite longitudinal sides of the X-axial arm, each of the Y-axial arms having a contact probe slidably attached thereto (see U.S. Pat. No. 5,107,206). The opposite contact probes can be brought to a desired coordinate position by driving the opposite Y-axial arms along the opposite longitudinal edges of the X-axial arm, and by driving the contact probes along the opposite Y-axial arms. The opposite Y-axial arms and the contact probes are driven quickly by associated servomotors through the agency of their rotating screws and nuts.
The X-axial arm supports the Y-axial arms on its opposite, longitudinal edges, and these arms are massive and heavy. Accordingly an increased driving power is required for transportation of each Y-axial arm.
To assure the exact positioning of the contact probes at a selected point in a printed circuit board the arms, guide members and other parts of the manipulator must be made of one and same material of good rigidity because otherwise, the thermal expansions of different parts at the surrounding temperature would cause an adverse effect in positioning the probe pin.
In testing complicated circuit structures two extra guard pins are necessitated, and therefore, four movable heads are required in all. All of these heads must be controlled so as to bring their probe and guard pins simultaneously to a selected small area of square millimeters. The four Y-axial arms equipped with such heads must be so arranged that no interference may be caused therebetween, and accordingly the whole manipulating structure is complicated. These Y-axial arms stand upright from the lying X-axial arm, and accordingly the vertical size of the manipulator is increased. What is worse is the lowered working efficiency caused by an increased force of inertia of the massive Y-axial arms, which prevents the movable parts from moving at an increased speed and high accuracy.
Therefore, there has been an increasing demand for a two-dimensional manipulator whose moving parts have decreased force of inertia small enough to assure the quick and accurate movement of contact probes (manipulating hands) and accordingly improve the working efficiency.